#include<stdio.h>

int main()
{
 	int sign=1;
 	double deno=2.0,sum=1.0,term;
 	while(deno<=100)
 	{
 		sign=-sign;
 		term=sign/deno;
 		sum=sum+term;
 		deno=deno+1;
	}
	printf("%f\n",sum);
 	return 0;
}

